Dr. Bill Mitsch presents on the problem of agricultural and urban run-off and possible solutions at the April 6 Lunch and Learn.

“Wetlaculture” offers proposed solution to filter aquatic ecosystems

Grace Cahill
May 9, 2018

The presence of excess nutrients resulting from agricultural and urban run-off poses an existential threat to streams, lakes and other aquatic ecosystems across the globe. However, while the problem may be extreme, Dr. Bill Mitsch, eminent scholar and director for the Everglades Wetland Research Park and Sproul Chair for Southwest Florida Habitat Restoration at Florida Gulf Coast University, suggested that the solution might be fairly simple in an April 6 Lunch and Learn presentation for the Ohio University Voinovich School of Leadership and Public Affairs.

Mitsch began his presentation by describing the unprecedented threats excessive nutrients pose to today’s aquatic ecosystems. Most excess nutrients are introduced to aquatic ecosystems through agricultural and urban runoff. More than 750 aquatic ecosystems currently suffer from degraded ecosystem services and impairments including oxygen deficiency or hypoxia, dead zones and harmful algal blooms; these stresses are mostly caused by excessive nitrogen and phosphorus pollution.

Mitsch cited a 2012 incident at Lake Okeechobee in Florida as exemplary of the dangers of excess nutrient levels. Due to flooding, polluted lake water full of sediment flowed into the Everglades, Caloosahatchtee River and St. Lucie River where it damaged sea-grass, oyster beds and game fish and triggered high bacteria levels that made swimming and fishing risky.

“The everglades agriculture area just below Lake Okeechobee is massively in the wrong place because the sugar farms use a lot of fertilizer that leaks into the Florida Everglades,” Mitsch said.

The inflow of dark lake water into the clear blue water of the Everglades was a shocking visual representation of how water resources had been mismanaged. Likewise, green algal blooms on the surface of Lake Erie have caused questions about the impacts of fertilizer runoff on the health of aquatic ecosystems. Both examples were well covered by the media and encouraged public awareness of the impacts of fertilizers on our lakes and rivers.

In Florida, public outrage over the pollution from Lake Okeechobee resulted in the creation of 50,000 acres of storm water treatment areas, what Mitsch prefers to call “treatment wetlands.” It has been estimated that, on a global scale, the world has lost half of its original wetlands since 1900. Mitsch believes that, as the example of Florida demonstrated, creating new, strategically placed wetland ecosystems can help to remove nitrogen and phosphorous pollution and potentially even mitigate the impacts of global warming.

“Their number one role is to take phosphorous out of the water, but of course, when you create wetlands you get all the other benefits, too,” said Mitsch. These other benefits include habitats that support diverse species of plants and animals, unique environments for recreation and education, and ecosystem services like storm protection and water purification.

The Everglades have been improved by the use of storm water treatment areas, and Mitsch believes that a similar concept he calls “wetlaculture” could do the same for Lake Erie’s nutrient-burdened waters.

Wetlaculture is a combination of the words “wetlands” and “agriculture.” Wetlaculture systems include wetlands intermixed with crops to filter out phosphorous and nitrogen from fertilizer runoff before these nutrients can reach lakes and rivers.

To Mitsch, the solution’s immense possibility is reflected in its simplicity. “This is the concept: fertilizer comes in, feeds the crops, waste fertilizer flows through wetlands, and clean water enters into lakes and rivers and is eventually taken to coastal waters,” he said.

Wetlaculture also presents economic benefits as well as environmental ones—when it is done properly, the fertilizers can be extracted and recycled.

“We would be able to stop—not slow down, but stop, using fertilizer” Mitsch said. This means that farmers could stop buying fertilizers entirely; combined with other incentives, Mitsch hopes the savings will convince farmers that wetlaculture is a viable business model.

According to Mitsch, the stakes are high, and reversing years of damage done to soil and watersheds will take time. “We need to do this for the next 100 years, we need to back off on the fertilizer systems. Our soil can’t accept any more nutrients and then the nutrients get into any lake or river downstream and cause havoc,” Mitsch said.

Despite the time necessary to fully address nitrogen and phosphorous pollution, Mitsch is optimistic. For now, he’s ready to start small by continuing to research how wetlaculture can be applied. “A wetland is born when you add water,” he said, and with that one new wetland comes new potential for sustainable change.